Alternating-current motor.



I No. 886,978. PATENTED NOV. 27, 1906.

M. G. A. LATOUR.

ALTERNATI'NG CURRENT MOTOR. APPLIGATION'IILED MAY 16, 1905.

Fig. I.

Witnesses. I Inventor.- ZM I MariusCJ Latour.

NITED s'rArns PATENT, OFFICE.

MARIUS O. ALLATOUR, OF PARIS,

FRANCE, ASSl-GNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF N EW- YORK. ALTERNATING-CU RREN T MOTOR.

Patented Na. 27, 1906.

Application filed May 16.1905. Serial No. 260.628. I

To all whom, it may concern: I

Be it known that I, MARIUS O. A. LATOUR, a citizen of France,'residing at Paris, France, have invented certain new and useful Improvements in Alternating-Current Motors, of which the following is a' specification.

My invention relates to alternating-current motors of the commutator type, and its obbecome the seat of heavy induced currents,

which result in poor commutation and lower the efiiciency of the motor. In'order to avoid these short-circuit currents, it has been proposed heretofore to provide the armature witha plurality-of independent windings connected to successive commutator-segments and to employ brushes of a width insuificient I to bridge adj acent segments connected to the same winding, By this arrangement the short-circuit currents are eliminated 1 and the operation of the motor at starting andat low .speeds is improved. This arrangement pos-v sessesa disadvantage at high speeds, however, since the circuit of one of the armaturewindings is broken every time that a. commutator-segment leaves a brush. At starting and at low speeds this objection is not serious, but at high'speeds severe sparking may result from this cause.

The object of my invention is to provide a novel arrangement of armature-windings which possess to a marked degree the advantages obtained at low speeds with a plurality of independent windings'without the disad-' vantage that has existed heretofore with such windings at high speeds.

My invention consists in providing 'the armature with a plurality of separate windingsand connecting equipotential points on these windings-to each other through suitable current-controlling devices and using brushes of a Width insufiicient to bridge adj acent segments connected to the same winding. In one form I employ resistances in these connections between the windings: With such an arrangement the resistances serveto prevent any heavy short-circuit currents from flowing at starting, while at high speeds, since the windings are connected in parallel at a plurality of points, only a portion of one of the windings is open-circuited when a commutator -segment leaves a brush. In

place of resistances permanently connected to the windings I may employ other currentcontrolling devices, such as switches.

My invention will best be understood by reference to the accompanying drawings, in which Figure 1 shows diagrammatically analternating-current motor with armature-windlllgS arranged in accordance .wlth my invention, and Fig. 2 shows a modified form of' the same.

In the drawings, A' represents the arma ture, which, for the sake of simplicity, is shown as a Gramme ring and which is pro vided with two separate windings. The two windings are connected to alternate segments of a commutator C. The commutatorbrushes B B are of such a width that they do not bridge two adjacent segments connected to the same winding. In other words,

7 they are not greater in width than the'width of a commutator-segment. I I

F F represent the field-poles of the motor. It should be understood that this representationis entirely diagrammatic and that a field structure with or without projecting poles and with a distributed or OOIICGlltIfitGClllGld-WiIlCling may be employedin practice. .1 Similarly, in actual construction the armature would preferably be of the drum type.

The two armature-windings are connected to each other at a number of equipotential .points by impedances R, which are preferably non-inductive resistances; It will be seen that whatever short-circuit currents "not diminish to any appreciable extent the advantage obtained by employing independent armature-windings. Moreover, at high speeds the commutation is very much better t an could be obtained without the cross connections. When a commutator-segment leaves a brush, only so much of thewinding to which that segment is connected is opencircuited as lies between the segment and the nearest cross connections. It is obvious that with such an arrangement the commutation is much better than when the entire circuit of one of the windings is broken every time a commutator-segment leaves a brush.

A different form of current-controlling device is shown in Fig. 2. In place of employing permanent cross connections with impedances included therein to limit thecurrentflow, switch-contacts may be inserted in these cross connections, so that at starting the two windings may be wholly independent, while at high speeds they may be connected directly to each other at a number of equipotential points. Theswitches may be con trolled manually or automatically.

In Fig. 2 l have shown an arrangement of switches designed to be operated automatically by centrifugal force. The switches are indicated at S. When the motor is at rest, the switches are held against stops in the position shown by tension-springs s, but are provided with suitable weights, so that when the motor reaches a certain speed the switches are moved outwardly against the tension of the springs and close. the connectionsbetween the two windings. Any other well-known type of automatic or manuallyo erated switch may be used in place of that s own.

Althou h I have shown an armature provided wit only two windings, it is obvious that any desired number of separate windings may be employed. Whatever the number of windings they should be connected to successive commutator-se ments, and the commutator-brushes shouId have a width insuflicient to bridge adjacent segments connected to the same winding. As has been before stated, I have illustrated my invention diagrammatically for the sake of simplicity, and any Well-known type of motor construction may be employed in carrying my invention into practice.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In an alternating-current dynamo-electric machine, an armature having a plurality of separate windings connected to successive commutator-segments, connections between a plurality of equipotential points on said windings, and commutatorbrushes of a width insufiicient to bridge ad'acent segments connected to the same win ing.

' 2. In an alternating-current dynamo-electric machine, an armature having a plurality of separate windings connected to successive commutator-segments, connections between a plurality of equipotential points on said -wind1ngs, current-controlling means in said tric machine, an armature having a plurality of separate windings connected to successive commutatorsegments,' connections between a plurality of equipotential points on said windings, non-1nduct1ve resistances inserted on said connections, and commutator-brushes of a Width insuflicient to bridge adjacent segments connected to the same winding.

In witness whereof I have hereunto set my hand this 5th day of May, 1905.

MARIUS C. A. LATOUR.

Witnesses:

HANSON C1. Coxn, JACK BAKER. 

